| Honorific Prefix: | General |
| Izaak Reijnders | |
| Office: | Commander-in-chief of the Armed forces |
| Term Start: | 28 August 1939 |
| Term End: | 6 February 1940 |
| Predecessor: | Vacant (1919-1939) Lieutenant general Willem Frederik Pop |
| Successor: | General Henri Winkelman |
| Birth Date: | 1879 3, df=yes |
| Birth Place: | Onstwedde, Netherlands |
| Death Place: | The Hague, Netherlands |
| Allegiance: |  Netherlands |
| Serviceyears: | 1896-1940 |
| Rank: | General |
Izaak Herman Reijnders (27 March 1879 – 31 December 1966) was in charge of the Dutch military high command just prior to World War II. He was replaced by Henri Winkelman after Reijnders had had an argument with Defense Minister Adriaan Dijxhoorn who repeatedly went behind his back and conspired to keep from him the authority that was lawfully his during the state of war. During the short German campaign in the Netherlands, May 1940, General Reijnders' predictions about the airborne assault on airfields in Holland, the German breakthrough at Mill, as well as the viability of the IJssel Line and Grebbe Line were proven spot on.